A false GPWS warning caused an air carrier medium large transport to climb from its descent path.

Attributes
ACN	254544
Time
Date	199310
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lax
State Reference	CA
Altitude	msl bound lower : 4600 msl bound upper : 5500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : lax
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach
Route In Use	arrival : profile descent arrival other arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 12000 flight time type : 1000
ASRS Report	254544
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

On a civet 4 profile descent to a runway 25L ILS, we received a GPWS 'terrain' warning. We were approximately 18 DME from lax at about 5500 ft MSL. Flight conditions were IMC with turbulence and rain. Upon receiving the GPWS warning, descent was stopped and a 300-400 FPM rate of climb was established. ATC was notified that we were discontinuing the descent due to a GPWS warning. Lax approach control confirmed our position and altitude so we requested to continue the approach. I called the 'a' flight attendant to the cockpit and had her check the cabin for anyone using any electronic devices, none were found. During all of the confusion, GPWS warnings and flight attendant in the cockpit, approach control asked us to level off at 5000 ft and turn left to a 220 degree heading. Our descent was not stopped until 4600 ft and we did not change heading until reconfirming the instructions with ATC. I find it very disturbing that a warning system like the GPWS can be allowed to disrupt ATC and cockpit communications because of its loud volume and its inability to be shut off. The GPWS warning finally stopped after about 1 min.

Original NASA ASRS Text

Title: A FALSE GPWS WARNING CAUSED AN ACR MLG TO CLB FROM ITS DSCNT PATH.

Narrative: ON A CIVET 4 PROFILE DSCNT TO A RWY 25L ILS, WE RECEIVED A GPWS 'TERRAIN' WARNING. WE WERE APPROX 18 DME FROM LAX AT ABOUT 5500 FT MSL. FLT CONDITIONS WERE IMC WITH TURB AND RAIN. UPON RECEIVING THE GPWS WARNING, DSCNT WAS STOPPED AND A 300-400 FPM RATE OF CLB WAS ESTABLISHED. ATC WAS NOTIFIED THAT WE WERE DISCONTINUING THE DSCNT DUE TO A GPWS WARNING. LAX APCH CTL CONFIRMED OUR POS AND ALT SO WE REQUESTED TO CONTINUE THE APCH. I CALLED THE 'A' FLT ATTENDANT TO THE COCKPIT AND HAD HER CHK THE CABIN FOR ANYONE USING ANY ELECTRONIC DEVICES, NONE WERE FOUND. DURING ALL OF THE CONFUSION, GPWS WARNINGS AND FLT ATTENDANT IN THE COCKPIT, APCH CTL ASKED US TO LEVEL OFF AT 5000 FT AND TURN L TO A 220 DEG HDG. OUR DSCNT WAS NOT STOPPED UNTIL 4600 FT AND WE DID NOT CHANGE HDG UNTIL RECONFIRMING THE INSTRUCTIONS WITH ATC. I FIND IT VERY DISTURBING THAT A WARNING SYS LIKE THE GPWS CAN BE ALLOWED TO DISRUPT ATC AND COCKPIT COMS BECAUSE OF ITS LOUD VOLUME AND ITS INABILITY TO BE SHUT OFF. THE GPWS WARNING FINALLY STOPPED AFTER ABOUT 1 MIN.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.